1. Field of the Invention
The prevent invention relates to a water in oil type emulsion explosive, particularly a water in oil type emulsion explosive composed of a continuous phase consisting of a carbonaceous fuel, a dispersive phase consisting of an aqueous solution of an inorganic oxidative salt, an emulsifier, a foam retainer, and an auxiliary sensitizer.
2. Related Art Statement
Recently, many studies on water in oil type emulsion explosive have been reported. Among such reports, there are known water in oil type (to be referred to as "W/O type", hereinafter) emulsion explosive not containing an explodent sensitizer such as trinitrotoluene or trimethylenetrinitramine, etc. and containing an auxiliary sensitizer such as monomethylamine nitrate or hydrazine nitrate, etc. and having an improved detonability of a blasting cap and an improved sympathetic detonation property, as disclosed by Japanese Patent Application Laid-open Nos. 60-51,685 and 60-90,887.
Though the W/O type emulsion explosive disclosed by the above Official gazette do not contain an explodent sensitizer, they contain an auxiliary sensitizer. Therefore, in case when they are used for blasting rocks of a high temperature or in an atmosphere of a high temperature caused by a pressurized state of a blasting hole, the explosives are liable to be decomposed. Such decomposition at the time of blasting is likely to lead an accidental detonation, and has a risk of incurring a gas explosion if a combustible gas is present in the environmental atmosphere of drifts of coal mines or the like. Hence, the W/O type emulsion explosive must be improved.